HIGH PERFORMANCE --- The 7-pin plug tester is made of high-quality ABS and copper with a frosted surface for durability and reliable use, ensuring maximum strength and durability for long-term use. You will need such a useful trailer tester tool. APPLICATIONS & SPECIFICATIONS --- The trailer plug tester is widely used for 12V caravans, motorhomes, recreational vehicles, vehicles, trailers and more. Dimensions: approx. 20 * 5 * 4 cm; Battery type: 9V (not included, you need to buy extra) Function --- One side of this trailer wiring tester is connected to the 7-pin plug of the trailer, and the other side is connected to the 7-pin socket of the car. Reliable quality - the performance of the trailer plug light tester is safe and reliable, and the design is reasonable.